Car running Lean

[dsmclipse97]

Ok guys, this problem has been plagueing me for some time now, I wanted to fix it myself but ive finally given up. when my car hits around 3k rpm's my narrowband goes lean. with my wastegate set at 5 psi, the car goes rich again around 1.5-2k rpms later and stays that way untill redline. At 7psi, the car stays lean and doesnt go rich again. Yes, yes i know my motor is at risk but i needed to see if the problem was boost or RPM related. This would obviously point out a restriction in my fuel system. My FMU is hooked up correctly and has no boost leaks from the vacuum line but it in the new model fuel system so the FMU is located next to the fuel tank. The last thing i can think of is maybe i need bigger injectors? i know the hahn kit comes with slightly larger injectors that dont need engine management to run. If so, where can i get a cheap set of injectors that will work? I should mention that my turbo is a tad on the small side, a garrett T3 .42 A/R. not sure if that would make any difference. My profile is up to date. Any advice would be helpful before i grenade my motor out of frustration. thanks.

 

[4UH8ERS]

Ok guys, this problem has been plagueing me for some time now, I wanted to fix it myself but ive finally given up. when my car hits around 3k rpm's my narrowband goes lean. with my wastegate set at 5 psi, the car goes rich again around 1.5-2k rpms later and stays that way untill redline. At 7psi, the car stays lean and doesnt go rich again. Yes, yes i know my motor is at risk but i needed to see if the problem was boost or RPM related. This would obviously point out a restriction in my fuel system. My FMU is hooked up correctly and has no boost leaks from the vacuum line but it in the new model fuel system so the FMU is located next to the fuel tank. The last thing i can think of is maybe i need bigger injectors? i know the hahn kit comes with slightly larger injectors that dont need engine management to run. If so, where can i get a cheap set of injectors that will work? I should mention that my turbo is a tad on the small side, a garrett T3 .42 A/R. not sure if that would make any difference. My profile is up to date. Any advice would be helpful before i grenade my motor out of frustration. thanks.

CRAP! I had to read that 4 times to comprehend what you were trying to say.

let me get this straight.

Wastegate set at 5psi:
When you hit 3k RPM's your narrowband starts to read a lean condition.
(I am assuming this is when you start to make the transition from vacuum to boost?)
As you continue to increase RPM's to around 4.5-5k you then begin to read a rich condition on your crappy narrowband.

Wastegate at 7psi:
The narrowband detects a lean condition throughout the entire RPM range.? or just once you hit 3K+.

What your sayin almost doesn't make any sense because of the fact that changing a wastegate setting from 5psi to 7psi should not effect the vehicle any differently until it surpasses the previous restriction of 5psi. Your injectors are most likely not the problem. Do a standard fuel problem trouble shooting procedure.
1. Change your fuel filter
2. Test your fuel pressures at idle and at WOT
3. Test voltage to the fuel pump
4. Make sure your running 91 or 93 Octane
5. Test Map sensor and FCD
6. check spark plug Gap et cetera.

(do the little things and record you results, because you need to know these variables in the first place to troubleshoot future issues, and you might just stumble on your problem.)

 

[BigRand]

This sounds like a vacume issue to me. It sounds like once your car transitions into boost its a little slower reacting to the change, that usually means your fuel presssure regulator or FMU isn't receiving the boost pressure signal as fast as the motor is getting boost. If I were you I would check that whole vac line, and your probably going to find an answer there.

I know you said you checked it, but you might also consider where the vacume source is coming from and how many times its been teed.

 

[link16]

Or run a vac tube from the nipple on your turbo compressor housing to the FMU that is what Hahn says in the instructions.

 

[dsmclipse97]

At 3K RPMs the car is already running 3-4 psi of boost. At 5 psi, the car will go rich again. with the wastegate set at 7psi it will not. Like i said, the turbo is quite small and i have already changed my vacuum source twice with no change. Thanks 4UH8ERS, ill check those random fuel components this weekend. Link16, you mentioned a vacuum source nipple on the turbo compressor? Should my turbo have one or would i need to tap one because im pretty sure mine has no such nipple. thanks for the input.

 

[BigRand]

Well first if you have no nipple source on the turbo how is your wastegate connected?

2nd: your narrow band gauge is probably going to be about 300-500rpm's behind what is actually happening.

3rd: If you have a 7psi spring in the wastegate, and have a FMIC, you should see a pressure drop of about 1.5-2psi on your boost gauge if you sourced it at the intake manifold like your supposed too. With that said.

Make sure you understand that you cannot set the wastegate any lower without changing the spring inside. So please be clear on how you use the term "adjust".

So go ahead and explain exactly what is happening in detail (w/ paragraphs or make it easy to read)

You do not need bigger injectors if your running the 12:1 FMU set up below 9psi on that turbo.

 

[VelocitàPaola]

Well first if you have no nipple source on the turbo how is your wastegate connected?

You can connect the WG directly to the intake manifold. Some people say vacuum on the WG, as opposed to just boost, is determintal to the device. I had my vacuum lines situated like for ages before I tapped my turbo's compressor housing, and I didn't notice any negative effects.

 

[BigRand]

You can connect the WG directly to the intake manifold. Some people say vacuum on the WG, as opposed to just boost, is determintal to the device. I had my vacuum lines situated like for ages before I tapped my turbo's compressor housing, and I didn't notice any negative effects.

Diagram please?

 

[dsmclipse97]

My WG is connected to the intake manifold like paul said. That was the recommended way that turbonetics stated in their evolution external WG manual. I have 5, 7 and 9 psi WG springs that i switch between. By "adjusting my boost" i mean that i am switching between springs. I have no boost controller. All i am saying is that my car is running lean AFTER i am hitting boost. The gauge doesnt go lean till around 3k RPM's but i start hitting boost at 2-2.5k RPMs), this would indicate that my FMU is working properly. It is possible that my A/F gauge is wrong but i blew off an intake pipe a few weeks ago and the gauge would read "rich" at WOT throughout the RPM band when my car was not seeing boost. Im sorry if i am confusing anyone but it is slightly difficult to explain.

 

[VelocitàPaola]

Diagram please?

Still out of town... I'll post it on Monday.

 

[BigRand]

Okay I'm gonna try to clearly explain my reasoning for it still being an FMU problem.

When you hit boost or start going into boost at 2k-2.5k, your wastegate is just opening correct and per pound of boost the fmu is supposed to raise the fuel pressure by 12psi. Believe it or not the stock injectors and stok regulator probably have enough fuel in them to handle 1 or 2psi before needinghelp so the gauge wil go lean at anything higher if the FMU doesn't kick on right away. However once you get to 5psi you said it goes rich, this could mean that the fmu has finally kicked on and the delay in response to the boost pressure is nullified.

Please keep in mind that your narrow band does not respond in realtime, there is a delay between what you see on the gauge and when that point in the fuel map that air fuel occurred.

 

[dsmclipse97]

Thanks Rand for the advice, it had occured to me that the FMU could not working properly. however, with no FMU, the car goes lean instantly when seeing boost (I had mine hooked up to a capped vacuum line so it saw no boost.) But lets also consider the possability that the FMU is just slow and when it reached 5 psi, the FMU catches up and it runs rich again. But as i explained earlier, with the WG at 7 psi, the car stays lean and does not go rich again. If the FMU was simply slow, wouldnt it catch up again at 7psi as it did at 5psi? And yes i know that narrowbands are pieces of junk but i ###### would have grenaded my engine by now without mine. And yes, i also realize they do not display real time data but it should still be very rich at any time during WOT not bouncing back to lean. Im thinking about relocating my FMU to the engine bay to see if that helps. does anyone know the best way to accomplish this? thanks again.

 

[Shadow98]

Are you sure you got the 12:1 disk in your FMU?

 

[dsmclipse97]

good question, i have an ebay FMU modeled after the vortech unit. It came shipped in the box marked as a 12:1 FMU. now whether or not they actually sent me a 12:1 i do not know. Is there any way to find out because it is not stamped anywhere on the outside.

 

[Locke]

Test it. Use (br)+f=F; where b=boost pressure, r=FMU ratio, f=base fuel pressure, F=working fuel pressure.

With 50psi fuel pressure base and a 12:1 disc, at 0 boost you should have 50psi FP still. at 5psi boost, your fuel pressure should be 110psi. At 8psi boost your fuel pressure should be 146psi.

 

[BigRand]

Yeah see if you can get your hands on a fuel pressure tester (pretty much like a compression testor) and plug it into the test port on the passenger side of the fuel rail, then run it up and under the hood so you can see it through the windsheild from the passsenger seat of the car. Have a friend tell you what the number is at 0 boost, and when you reach your 5 psi.

 

[VelocitàPaola]

Test it. Use (br)+f=F; where b=boost pressure, r=FMU ratio, f=base fuel pressure, F=working fuel pressure.

With 50psi fuel pressure base and a 12:1 disc, at 0 boost you should have 50psi FP still. at 5psi boost, your fuel pressure should be 110psi. At 8psi boost your fuel pressure should be 146psi.

Or just measure the disk -- it's 2.72" dia. I believe...

 

[Locke]

I was originally going to mention just that! Then I remembered that I don't know anything about disc sizes. Someday, when I have a need to.